1. Field of the Invention
The present invention relates to a sample dispensing apparatus and method. More particularly, it relates to a sample dispensing apparatus for and a method of dispensing a sample by use of a disposable nozzle tip, unloading the dispensed sample to a transfer line, and transferring it to an analyzer or the like.
2. Description of the Related Art
For example, Japanese Patent No. 3410018 describes a dispensing apparatus in which after a sample is sucked by a nozzle tip disposable for each sample therein, the sucked sample is delivered into a secondary sample vessel to automatically dispense a sample such as blood an urine by a certain quantity necessary for analysis and inspection, from one vessel (primary sample vessel) to another (secondary sample vessel). If a sample to be subjected to analysis is a serum constituent, blood containing a separating agent having intermediate specific gravity and high viscosity and stored in the primary sample vessel, is separated into three layers (serum constituent, separating agent, and blood clot constituent) by use of a centrifugal separator. The separating agent is used between the serum constituent and the blood clot constituent to prevent the three layers from being re-mixed. In a sample dispensing apparatus, dispensing is performed to use only the serum constituent for analysis. When the serum constituent in the primary sample vessel is sucked into the nozzle tip by a required quantity, if the quantity of the serum constituent is not sufficient, the opening at the free end of the nozzle tip comes into contact with the separating agent, resulting in clogging. In this case, the serum constituent already sucked when clogging has been detected is delivered to the secondary sample vessel, while it is necessary to decrease the serum constituent left in the primary sample vessel. A relevant technique is disclosed in, for example, JP-A-7-27679. With this technique, if clogging occurs, the serum constituent sucked in the nozzle tip is returned and then re-sucked.
When a sample is sucked, if the quantity of the sample is less than the specified quantity to be sucked, the opening at the free end of the nozzle tip comes into contact with the separating agent before the sample is sucked up as specified, resulting in clogging. Suction is stopped when clogging has been detected and then the sample sucked until detection of the clogging is dispensed into the secondary sample vessel. To decrease the serum constituent remaining in the primary sample, JP-A-7-27679 proposes a technique of returning the serum constituent sucked into the nozzle tip and then re-sucking it if clogging occurs. With this technique, however, since the serum constituent is returned and then re-sucked, it takes much time for processing and the primary sample is disturbed, which may damage the sample.
An object of the present invention is to provide a sample dispensing apparatus and method which dispenses a sample (primary sample) such as blood and urine collected for inspection from one vessel to another, wherein the remaining quantity of a primary sample can be reduced without disturbing of the primary sample.
The above-mentioned object of the present invention can be attained by, when clogging of an opening at the free end of a nozzle tip caused by a separating agent is detected, raising an aliquot head such that the opening at the free end of the nozzle tip does not come out of the liquid surface of serum constituent to dissolve the clogging; sucking the serum constituent under the residual pressure; and additionally sucking a fixed quantity thereof after the residual pressure drops.
In accordance with the present invention, it is possible to decrease the sample that would be left in a primary sample without disturbing the primary sample by raising an aliquot head such that an opening at the free end of a nozzle tip does not come out of the sample liquid surface to dissolve clogging, sucking serum constituent under the residual pressure, and then additionally sucking the same.